C·I·B study explores the role of heat treatment in active restoration of Fynbos

A recent paper by C·I·B student, Stuart Hall, found that heat pre-treatment of seeds can improve restoration
efforts in fynbos ecosystems that were cleared of invasive alien tree species. The paper was co-authored by C·I·B Core Team
Members, Mirijam Gaertner and Karen Esler, and C·I·B Research Associate, Patricia Holmes.

In areas where invasive alien plants have been removed there may be a need for reintroducing seed of fynbos species to
re-establish a functional ecosystem. Much work has been done on the effect of smoke on germination, but few studies on the effect of heat
treatment. The study, which was conducted on seeds of species from Blaauwberg Nature Reserve, compared the effect of different temperatures
and times of exposure on the germination of a range of species that are typical of fynbos vegetation.

After grouping the seeds according to their response to the heat treatments, Stuart identified two main groups. One group was
stimulated by smoke without heat, or extended exposure to mildly high temperatures, or did not require any germination cues. These species
were in most cases sensitive to temperatures above 60 degrees Celsius. The other group of species needed exposure to higher temperatures,
germinating best at exposure to 100 degrees Celsius, and not germinating optimally without heat exposure.

According to Stuart, “our study gives us a guideline of what species require heat treatments when planning active
restoration involving sowing seeds of native species. Previous fynbos heat studies involved species mostly within the pea family (Fabaceae).
Our study showed that species from genera in other families (Trichocephalus within Rhamnaceae and Pelargonium within Geraniaceae) also
respond to heat and smoke treatment, which was not previously proven within the fynbos.”

“Our study further suggests what species are likely to experience depleted seed banks as a result of fires in
ecosystems invaded by alien invasive species,” explains Stuart, lead author of the paper in Austral Ecology.

This study was done in collaboration with Kew and the research undertaken at the Millennium Seed Bank, with financial support from the
Bentham Moxon Trust and the Arcadia Fund, as well as the Working for Water Programme through their collaborative research project on
“Integrated Management of invasive alien species in South Africa”.